Portable power bank



FIG. 1 is a perspective view of the portable power bank showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines in the drawings are for the purpose of illustrating portions of the portable power bank, that form no part of the claimed design. 

CLAIM The ornamental design for a portable power bank, as shown and described. 